Aircraft and other complex apparatuses include a myriad of interoperating components. Many subsystems of components are designed for maintenance and/or repair. When such a subsystem or component performs unexpectedly (e.g., it becomes non-responsive or functions with degraded performance), the operation of the aircraft may be impacted and the aircraft may be subject to unscheduled maintenance and down time. As an example, servomechanisms operating flight control surfaces of aircraft may become non-operational and may consequently result in strain on the flight control system, fuel waste, aircraft down time, excess troubleshooting, strain on the replacement part supply, and/or potential stress on other aircraft components and systems. The consequences of an unexpected need to repair or an unexpected repair of the non-performing component may be much greater than the cost, in time and resources, to repair or replace the non-performing component.
For many components, operators currently have no insight into the health of the components. Moreover, subsystems and components may behave erratically and unexpectedly well before complete non-performance. The behavior of components that may lead to non-performance may manifest as merely non-specific system degradation and related effects.
Aircraft may be available for maintenance and diagnosis only between flights. If a component performs unexpectedly during a flight, the non-performing component may require an abrupt end to the flight, necessitating a return trip for repair or at least temporary abandonment of the aircraft.
If a component does not pass pre-flight tests, the component may need to be repaired or replaced before the next flight. After a component has performed unexpectedly during a flight and resulted in noticeable system performance degradation, maintenance staff may troubleshoot the aircraft function and eventually identify the non-performing part as a contributor to the observed system performance degradation. The unscheduled down time and maintenance to identify the issue and to repair or replace the non-performing component may lead to resource conflicts with the aircraft. The aircraft typically is unavailable for use during troubleshooting and repair. Additionally, the unscheduled down time and maintenance may lead to strains on the scheduling of maintenance personnel due to excess time troubleshooting and identifying the issue, and may lead to strains on the supply chain for replacement parts because the need for parts may not be predictable. This reactive response to non-performing components may be inefficient when compared to scheduled maintenance or a proactive response to impending component non-performance.
Further, aircraft may include components designed to last the service life of the aircraft and not specifically designed for maintenance and/or repair. For example, airframe components generally are expected to function for the service life of the aircraft. However, some components may not react to the stresses of use and the environment as expected and some aircraft may be used beyond the originally designed service life. In such cases, repair or replacement of structural components not originally designed to be repaired or replaced may cause significant downtime for individual aircraft while the affected structural components are repaired or reproduced for replacement.
For example, the F/A-18 Hornet model of aircraft was first placed into operational service in 1983. Now more than 30 years later, the majority of F/A-18 Hornet aircraft in service are operated at or beyond their originally designed service life (6,000-8,000 hours). Continued operation relies on a structured approach to inspection, maintenance, and repair that includes airframe repair and replacement. Airframe inspection, repair, and replacement are performed during cycles of heavy maintenance. During heavy maintenance, the airframe and other structural components are inspected for mechanical wear, heat damage, corrosion, and other signs of component fatigue. Though heavy maintenance commonly results in repair or replacement of some structural components, predicting which components will need repair or replacement in a particular aircraft is very difficult with current technology. Hence, maintaining the F/A-18 Hornet fleet in serviceable condition leads to new and variable demand for a large number of airframe and other structural components that were not originally designed to be repaired or replaced. Additionally, heavy maintenance results in unpredictable downtime for individual aircraft due to the variable demand for repaired or replacement components and the time to repair, reproduce, and/or replace the affected components.